Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS62 KRAH 011951
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
250 PM EST SUN MAR 1 2015

.SYNOPSIS...A DISTURBANCE WILL EXIT THE REGION BY THIS EVENING. WEAK
BUT COOL HIGH PRESSURE WILL HOLD OVER THE AREA THROUGH TONIGHT. A
COLD FRONT WILL PUSH SOUTHWARD THROUGH NORTH CAROLINA ON MONDAY...
THEN SETTLE JUST TO OUR SOUTH MONDAY NIGHT AS HIGH PRESSURE NOSES IN
FROM THE NORTH. MOIST AIR RIDING UP AND OVER THIS STATIONARY FRONT
WILL BRING UNSETTLED WEATHER FOR TUESDAY INTO WEDNESDAY.

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 210 PM SUNDAY...

THROUGH TONIGHT: FAIRLY DEEP MOIST ISENTROPIC UPGLIDE ATOP A CHILLY
IN SITU WEDGE AIR MASS CONTINUES TO PRODUCE AREAS OF LIGHT RAIN AND
DRIZZLE OVER CENTRAL NC. THE LOSS OF A FEED OF LOW LEVEL DRY AIR IN
TO THE AREA TO COUNTERACT THE EFFECTS OF LATENT HEAT RELEASE HAS LED
TO A SWITCHOVER TO MOSTLY FREEZING RAIN OVER ALL BUT THE FAR
NORTHERN PIEDMONT... AND EVEN HERE IT DOESN`T APPEAR THAT ANY
ADDITIONAL ICE IS ACCRUING GIVEN THE NEAR-FREEZING WET BULBS. TRENDS
ALL SUGGEST THAT WE CAN LET WHAT`S LEFT OF THE ADVISORY EXPIRE ON
SCHEDULE OR PERHAPS BE CANCELLED A BIT EARLY. THE SUPPORTIVE
MOIST UPGLIDE WILL BE ON THE WANE THROUGH THE LATE AFTERNOON AND
EARLY EVENING... AS THE WEAK 850 MB WAVE HEADS TO OUR NORTHEAST...
AND MODEL GUIDANCE ALL POINT TO AN EXIT OF THE RAIN TO THE NORTHEAST
THIS EVENING. WILL MAINTAIN A WEST-TO-EAST TAPERING OFF OF POPS
ACROSS THE CWA. A WEAK SURFACE MESOHIGH WILL HOLD OVER THE WESTERN
AND CENTRAL CAROLINAS OVERNIGHT... WITH A WEAK REMNANT COASTAL FRONT
ON ITS EASTERN EDGE AND THE MOUNTAINS ON ITS WESTERN EDGE HINDERING
ANY HORIZONTAL DISPERSION... AND A CONTINUED STABILIZING WARM SURGE
ALOFT PREVENTING VERTICAL DISPERSION. EXPECT LOW CLOUDS AND FOG TO
HOLD TONIGHT WITH HIGHLY STABLE AND MOIST LOW LEVELS. THIS PATTERN
AS WELL AS STATISTICAL GUIDANCE SUPPORT TEMPS MOVING VERY LITTLE
OVERNIGHT... HOLDING AT ROUGHLY 32 TO 40. TOO MUCH UNCERTAINTY RIGHT
NOW REGARDING STRATUS VERSUS FOG DOMINATING TONIGHT... BUT IF OUR
SURFACE WINDS DROP TO LESS THAN 4 KTS FOR AN EXTENDED TIME... WE MAY
NEED A DENSE FOG ADVISORY FOR A PORTION OF THE CWA OVERNIGHT.

FOR MON/MON NIGHT: A POTENT NORTHERN STREAM SHORTWAVE TROUGH
CROSSING THE GREAT LAKES/ST LAWRENCE VALLEY/NORTHEAST LATE
TONIGHT/MONDAY WILL HELP PUSH A WEAK FRONT SOUTHWARD INTO AND
THROUGH NC MONDAY... AND AFTER A MURKY AND GRAY MONDAY MORNING...
THIS MECHANISM WILL FINALLY SCOUR OUT THE LOW LEVEL MOIST/STABLE
POOL FROM NNW TO SSE DURING THE DAY. MODELS DEPICT ENOUGH LOW AND
MID LEVEL MOISTURE HOLDING ON OVER SRN NC NEAR THE SOUTHWARD-INCHING
FRONTAL ZONE WITH SUFFICIENT LINGERING LOW LEVEL MOISTURE TRANSPORT
TO SUPPORT A LOW CHANCE OF SOME PATCHY LIGHT RAIN OVER THE SRN CWA
MON FROM LATE MORNING THROUGH MID AFTERNOON... WHILE FURTHER
NORTH... WE SHOULD TREND TOWARD PARTIAL CLEARING AS DRIER LOW LEVEL
AIR ATTEMPTS TO BUILD IN. HAVE OPTED TO STAY ON THE LOW END OF
GUIDANCE FOR HIGHS MONDAY (NEAR 50 NORTH TO THE UPPER 50S SOUTH) AS
THERE IS LIKELY TO BE A DELAY AND LIMIT TO THE PARTIAL CLEARING...
HOWEVER IF LATER FORECASTS TREND TOWARD MORE SUNSHINE TOMORROW...
THESE MAY NEED TO BE BUMPED UP A CATEGORY OR SO. THE RELATIVELY
QUIET WEATHER WILL BE SHORT-LIVED... NOT A SURPRISE GIVEN THE STRONG
JET LEVEL WINDS OVER THE CENTRAL/SRN CONUS FOSTERING AN ACTIVE
WEATHER CYCLE. AN APPROACHING WEAK LOW LEVEL WAVE AND PRECEDING
SURGE IN MOISTURE TRANSPORT INTO THE MIDSOUTH AND SOUTHERN
APPALACHIANS WILL SUPPORT A SMALL CHANCE POP IN THE SW CWA LATE MON
NIGHT. LOWS FROM AROUND 30 NE TO MID-UPPER 30S FAR SOUTHWEST. -GIH

&&

.SHORT TERM /TUESDAY/...
AS OF 250 PM SUNDAY...

A CAD SCENARIO IS PROGGED TO DEVELOP ON TUESDAY AS A 1032 HIGH TO
OUR NORTH DRIFTS EAST OUT INTO THE ATLANTIC...AND FLOW ALOFT BACKS
FROM WNW IN THE MORNING TO SW BY AFTERNOON. WITH ISENTROPIC UPGLIDE
INCREASING AS 850MB FLOW BACKS TO SW AND INCREASES...LOOK FOR LIGHT
RAIN TO DEVELOP TUESDAY MORNING AND LINGER INTO THE AFTERNOON...WITH
MODELS SUGGESTING QPF WILL REMAIN AOB 0.15". AS ALWAYS THE CASE WITH
CAD...TEMPS WILL REMAIN BELOW GUIDANCE AND WELL BELOW NORMAL...UPPER
30S NW TO AROUND 50 SE. WHILE WE HAVE LOW TEMPS AROUND FREEZING
ALONG AND NORTH OF HWY 64 TUESDAY MORNING...THE COMBINATION OF THE
LIGHT INTENSITY OF THE RAIN AND BORDERLINE FREEZING TEMPS...FORECAST
SOUNDINGS SUGGEST VERY LITTLE IF ANY FREEZING RAIN THREAT ACROSS OUR
NORTHERN ZONES TUESDAY MORNING.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
AS OF 250 PM SUNDAY...

TUESDAY NIGHT...THE NEXT COLD FRONT WILL APPROACH...AND WITH
INCREASING SW LOW LEVEL FLOW AHEAD OF IT...THE CAD SHOULD SCOUR OUT
WITH TEMPS TUE NIGHT ACTUALLY RISING THRU THE NIGHT WITH VIGOROUS
WAA AHEAD OF THE FRONT. IN FACT...BY- OR SHORTLY AFTER SUNRISE
WED...TEMPS WILL BE IN THE 50S ACROSS OUR ENTIRE CWA. WITH FROPA
DURING THE AFTERNOON...WE COULD SEE TEMPS RISE WELL INTO THE 60S
DURING THE MORNING...PERHAPS BREAKING THE 70 DEGREE MARK ACROSS OUR
SE ZONES. AS FOR RAIN CHANCES...LOOK FOR POPS TO INCREASE FROM NW TO
SE THRU THE DAY WED...WHILE IT STILL LOOKS LIKE THE BULK OF THE
PRECIP WILL BE FOUND RIGHT ALONG OR JUST BEHIND THE FRONT...WHICH
WILL LINGER WEDNESDAY NIGHT THROUGH MUCH OF THE DAY THURSDAY AS
MIDLEVEL FLOW BECOMES PARALLEL TO THE FRONT...AND A STEADY FETCH OF
DEEP MOISTURE IS TRANSPORTED OVERTOP A COOLING POST-FRONTAL LOW
LEVEL AIRMASS. SPEAKING OF THE COOLING LOW LEVEL AIRMASS...LOW LEVEL
THICKNESSES ARE PROGGED TO PLUMMET IN THE WAKE OF THE FRONT...FROM
~1380M 00Z THU TO ~1265M BY 10Z THU. SOME OF THE GUIDANCE SUGGESTS
TEMPS MAY HOLD IN THE 20S DURING THE DAY THU!  GIVEN THE
AFOREMENTIONED LINGERING MOISTURE PLUME...ASSUMING THIS MODEL
SOLUTION HOLDS...ITS BEGINNING TO LOOK A LITTLE MORE LIKELY THAT WE
MAY BE DEALING WITH SOME SORT OF WINTER P-TYPE EVENT DURING THE
DAYTIME THURSDAY. THE MAIN QUESTION IS HOW MUCH...AS QPF PROGS STILL
VARY QUITE A BIT...WITH GFS QPF ROUGHLY TWICE AS MUCH AS THE ECMWF
DURING THE 12Z THU TO 00Z FRI PERIOD. PLEASE STAY TUNED!

LATEST GFS AND ECMWF ARE IN BETTER AGREEMENT DURING THE LATE-WEEK
AND WEEKEND TIMEFRAME...WITH THE OPERATIONAL RUNS BOTH SHOWING THE
MOISTURE PLUMES PUSHING SOUTH OF OUR CWA BY 06Z FRIDAY...THEN DRY
WEATHER FOR OUR CWA FRIDAY THROUGH SATURDAY WITH HIGH PRESSURE
BUILDING OVER THE AREA. LOW LEVEL THICKNESS PROGS RECOVER QUITE
QUICKLY DURING THIS TIME...BUT THAT MAY NEED ADJUSTMENT DEPENDING ON
WHAT HAPPENS THURSDAY.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
AS OF 1245 PM SUNDAY...

PRIMARY AVIATION CONCERNS NEXT 24 HRS: CONTINUED IFR/LIFR CIGS AND
MVFR/IFR VSBYS THROUGH TONIGHT... AND BORDERLINE LOW LEVEL WIND
SHEAR THIS EVENING/TONIGHT.

WIDESPREAD IFR/LIFR CONDITIONS PERSIST OVER CENTRAL NC TAF SITES
THIS AFTERNOON... ALONG WITH PATCHES OF RAIN (FAY/RDU) OR FREEZING
RAIN (RWI/INT/GSO). THIS FREEZING RAIN AT RWI/INT/GSO WILL TREND TO
JUST RAIN THIS AFTERNOON... FIRST AT RWI THEN AT GSO AND INT. ALL
LOCATIONS SHOULD BE JUST RAIN BEFORE 21Z. PERIODS OF RAIN WILL TAPER
OFF AT INT/GSO BY 22Z THIS AFTERNOON... AT RDU BY 00Z THIS
EVENING... AND AT FAY/RWI BY 04Z LATE THIS EVENING. WITH FAIRLY
LIGHT SURFACE WINDS OVERNIGHT AND A MOIST GROUND... CONFIDENCE IS
HIGH THAT IFR/LIFR CONDITIONS WILL HOLD THROUGH AT LEAST 12Z MON AT
ALL TAF SITES. AS A WEAK FRONT DROPS SOUTHEAST INTO THE AREA
MONDAY... CAUSING SURFACE WINDS TO SHIFT FROM LIGHT SW TO BE FROM
THE NW... THESE LOW CLOUDS/FOG WILL SCOUR OUT GRADUALLY TO VFR BY
THE 16Z-18Z MONDAY TIME FRAME AT INT/GSO... WITH LOWER CONFIDENCE IN
THIS OCCURRING PRIOR TO 18Z AT RDU/RWI/FAY. LOW LEVEL WIND SHEAR
THREAT REMAINS MARGINAL AND FOCUSED AFTER MIDNIGHT TONIGHT AT
FAY/RDU/RWI... AS 1000-1500 FT AGL WINDS BECOME WESTERLY AT 25-30
KTS.

LOOKING BEYOND 18Z MON... VFR CONDITIONS SHOULD PERSIST FROM EARLY
TO MID AFTERNOON MONDAY THROUGH MONDAY NIGHT... AS THE SURFACE FRONT
SETTLES ALONG THE SRN NC BORDER WHILE HIGH PRESSURE NOSES IN FROM
THE NORTHWEST. HOWEVER... A DISTURBANCE ALOFT RIDING ALONG THE
SURFACE FRONT WILL BRING A THREAT OF MVFR/IFR CONDITIONS STARTING
LATE MONDAY NIGHT (INT/GSO) OR TUE AFTERNOON (RDU/RWI/FAY)... ALONG
WITH A LLWS RISK. THESE SUB-VFR CONDITIONS SHOULD GIVE WAY TO VFR
CONDITIONS AT FAY THEN AT RWI/RDU WED AS A WARM FRONT MOVES
NORTHWEST THROUGH THE AREA WITH STRENGTHENING SW WINDS... BUT SUB-
VFR CONDITIONS MAY HOLD IN LONGER AT INT/GSO. THIS WARM FRONT WILL
DROP BACK DOWN SOUTHEAST THROUGH THE AREA AS A COLD FRONT LATE WED
OR WED NIGHT... TURNING SURFACE WINDS BACK AROUND TO
NORTH/NORTHEASTERLY FOR THU WITH WIDESPREAD RAIN AND SUB-VFR
CONDITIONS. VFR CONDITIONS SHOULD RETURN TO NORTHERN SECTIONS
(RDU/RWI/INT/GSO) BY THURSDAY NIGHT/FRIDAY. -GIH

&&

.RAH WATCHES/WARNINGS/ADVISORIES...

WINTER WEATHER ADVISORY UNTIL 4 PM EST THIS EVENING FOR
NCZ007-021>023-038-039.

&&

$$
SYNOPSIS...HARTFIELD
NEAR TERM...HARTFIELD
SHORT TERM...RAH
LONG TERM...RAH
AVIATION...HARTFIELD


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.